This invention relates to a protective device for protecting against embolization during carotid by temporarily reversing antegrade flow of blood stream to prevent emboli from reaching the brain.
Although traditionally conventional open surgery has been used in treatments of vascular diseases, such as stenosis of carotid artery, nowadays endovascular treatments are preferred.
These treatments carried out in the lumen of the vascular duct, and have the advantage of being less aggressive than the above mentioned open surgery.
In the case of stenosis of the carotid artery, the vascular wall is affected by a pathologic narrowing that prevents blood from flowing normally. The treatment consists in an endovascular angioplasty, resorting to a balloon in order to expand the area with stenosis and, if necessary, to deliver a stent to cover said area.
The problem that this kind of treatment has is that, when the balloon is inflated or when the stent is placed, emboli can be formed which can rapidly reach the brain, with severe consequences.
In the search of minimizing such risks, research has been carried out, such as the Echodoppler system transcranial to measure the speed of blood in the middle cerebral artery, while the surgery on the carotid artery is carried out.
In normal conditions, blood flows in an antegrade direction, i.e., upstream, so that in the carotid artery it goes from the common carotid artery to the external and internal branches. During an operation, the artery is occluded and the flow decreases, depending on the degree of collateral flow and on connections with the Circle of Willis. After the occlusion has been made, a shunt is used as a temporary conduit. One end of the shunt is connected to the internal carotid artery, while the proximal end remains open. Since the common carotid artery is occluded, blood flow is reversed, thus draining emboli to the exterior of the patient""s body. This kind of treatment has enormous risks, however, since blood flow reversal can cause cerebral ischemia or hypovolemia.
It therefore would be desirable to provide a device that allows blood flow to be reversed under control, thus removing emboli generated by the angioplasty.
In view of the foregoing, a protective device against embolization is provided that overcomes the drawbacks of previously known devices and methods. The device comprises a guide catheter having a lumen, and a tubular member axially movable in the lumen and having a distal end expandable against the vascular walls of the carotid artery. The distal end includes a drainage port having non-folding edges that communicates with an outlet provided with a hemostatic valve and with an access way to the above mentioned lumen.
When the distal end of the tubular member is extended beyond the distal end of the catheter, it expands against the vascular walls. Once expanded, the distal end assumes the shape of a goblet, and the external non-folding edges occlude antegrade flow of blood. When the hemostatic valve is opened, a retrograde flow occurs that carries the emboli to the exterior of the body, where the blood may be cleansed and re-perfused. In this way, emboli are prevented from being driven by the antegrade flow to the brain through the vascular duct.
As regards the materials used for the tubular member, materials with similar properties to the known self-expanding stents can be used, such as described in Great Britain patent specification 1,205,743, to Didcott, although the material should be covered with an impermeable material in order to be part of this protective device against embolization.